1. Field of Invention
This invention relates to a biopsy instrument having a disposable cutting blade assembly and more particularly to an instrument which may be used to sever and remove a minute portion of a cervix in vivo.
2. Description of the Prior Art
Instruments for removing tissue samples in vivo and more particularly for removing cervix samples are known in the art. One such instrument is disclosed in U.S. Pat. No. 4,243,047 to Olsen. This prior art instrument comprises an elongated arm terminating in two blades which may be pivoted toward each other in a scissor action. It is important to keep the blades sharp to insure that the sample has a clean edge. A sample cut with a dull blade may be crushed, at least partially, so that it can't be used effectively for analysis. Furthermore, using an instrument with a dull blade could cause considerable discomfort to the patient. However, the blades disclosed by Olsen are fixed, i.e., an integral part of the instrument and therefore, after several operations, they must be sharpened by hand. Manual blade sharpening is labor intensive and therefor expensive. It can cost as much as $50.00 to sharpen the blades in such instruments. A further disadvantage of the Olsen device is that the blades are activated by two handles secured at one end of the arm and which must be reciprocated like the handles of a scissor. Because of the relatively large angular motion of these handles, it is very difficult to keep the instrument and particularly its cutting end steady while closing the blades.
U.S. Pat. No. 3,943,916 to Vadas discloses another instrument for removing a cervix sample; however, this instrument takes a conical tissue sample and accordingly requires a very complex cutting mechanism.
A biopsy instrument with a replaceable blade has been available from Gyneco of Branchburg, N.J. under the name of CIN-SHEAR. However, this instrument which employs a single cutting blade has proved difficult to use and does not provide optimal cutting. Other exemplary prior art forceps and scissors are made by various instrument manufacturers such as Karl Storz of Tuttlingen, West Germany, as illustrated in its Arthroscopy catalog, 1984 Edition. However, none of these instruments have removable blades and thus must be manually sharpened.